Re: DRAFT: eXIF 2017-05-28

Ok. After all reviews I choose to prefer safe-to-copy too.

But I think that purely historical safe-to-copy eXIf should be 
explicitly forbidden to use any other way, while current eXIF draft 
allows it to use EXIF data as property of current image itself.

This includes any kinds of PNG-to-JPEG (or PNG-to-TIFF or PNG-to-WebP) 
conversions. And for current eXIF proposal recommendations about fitting 
into APP1 looks like suggestions of direct using eXIF chunk as APP1. 
Actual eXIF may be used for direct APP1 in some cases, but historical 
eXIf never should be used this way.

So no simple PNG-to-EXIF conversion will be allowed for eXIf (I still 
doubt that such conversion could be simple enough for eXIF). And vice 
versa: no simple EXIF-to-PNG conversion with eXIf as any valuable data 
that could be applied to image must be copied to appropriate PNG chunks 
(incl. resolution, gamma, change date, software etc..).

Also some values of EXIF are unsafe-to-copy and have no appropriate PNG 
chunk: orientation, subject area/location. Not sure about digital zoom 
and camera elevation.


30.05.2017 14:03, Glenn Randers-Pehrson пишет:
> Just to be clear, I too greatly prefer eXIf (safe-to-copy) over
> eXIF (unsafe-to-copy) because it does a better job of preserving
> valuable historical information.  Approval of eXIf wouldn't
> require applications such as pngcrush/optipng to do anything
> new, while eXIF would require them to issue a new version
> to handle eXIF as if it were safe-to-copy when it's not
> making changes that would render that information
> incorrect.
>
> If you like, you may consider the eXIF proposal to be a
> strawman designed to resurrect the discussion of eXIf,
> which is still an active proposal despite discussion
> having lapsed.
>
> Glenn
>
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-- 
Have a nice DOS.

Pavel Zlatovratskii [email protected]; [email protected]


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